Metal-oxide-semiconductor field-effect transistors (MOSFETs) are used for amplifying or switching electronic signals. A MOSFET device used for power switching is sometimes referred to as a power MOSFET. Power MOSFET devices typically contain multiple individual MOSFET structures arranged in active cells. The switching frequency of MOSFET devices are limited by device characteristics, largely capacitances, and in the case of certain applications, namely DC-DC converters, the recovery of the parasitic diode inherent in all power MOSFET device structures. In the latter case, Schottky diodes are commonly connected in parallel to the MOSFET devices to improve the diode recovery portion of the devices switching behavior. Additionally, Schottky diodes have an added benefit of a lower forward diode voltage drop, which suppresses power loss in the non-switching portion of device operation.
However, the use of a Schottky diode in parallel with the MOSFET devices does have some drawbacks. First, Schottky diodes typically have high reverse bias current leakage which adversely affects the performance of the device. Additionally, the integration of a Schottky diode into an MOSFET device utilizes valuable space on the die that could otherwise be used for additional active devices. Further, the integration of a Schottky diode may increase the cost of manufacturing the MOSFET devices because additional mask sets may be needed to form the Schottky diode. Therefore, there is a need in the art for a Schottky diode that has minimal leakage and can be integrated into the device in a space conscious manner without needing additional masks.
It is within this context that embodiments of the present invention arise.